'yo' is a "sentence ender" that expresses a strong opinion on something, generally something the speaker thinks they know better than the listener. It doesn't actually have a translation, but a decent substitute in english would be "you know?" at the end of the sentence.

Without context, I presume "mama" here is what a child is calling his/her mother? If so, then the katakana is probably correct. But without context, I can't answer that for sure.